Method for preparing mats for use in making printing plates



Patented Apr. 29, 1930 Ufiif'i fifi STATES EARLE MARTIN, OF CLEVELAND, OHIO METHOD FOR PREPARING MATS FOR USE IItT MAKING PRINTING PLATES No Drawing.

This invention relates to the manufacture of stereotype plates, and more particularly to the preparation of mats that are used therein, and is an improvement on the invention described and claimed in my application Serial N 0. 295,356, filed July 25th, 1928.

The dry matrix process, now in common use in newspaper stereotype de artments, has not been entirely satisfactory ecause of the inability to produce stereotype plates of uniform size. It is important, in running an edition of a newspaper, to have the plates of uniform size because lack of uniformity results in a material loss of paper. When the plates vary in size the sheet of paper must be large enough to accommodate the largest plate,

and still leave the desired margin. It is apparent, therefore, that if the plates of an edition of a newspaper were of uniform size and that size was the minimum now used, then the size of the printed sheet could be gauged to this minimum, whereas it is now necessary to gauge the size of the sheet to the largest plate. The variation in the size of the stereotype plates is due to a variation in the amount of moisture in the mats. The mats are made of papier-mach and swell when moistened and shrink when dried. The mats are moistened before being subjected to the pressure of the typeform, for the purpose of making the matrix. It is, therefore, important to have the mats uniformly moistened so that, when dried, they will shrink to a uniform size.

it is an object of the present invention. to provide a method of moistening the mats and maintaining a uniform amount of moisture therein so as to insure uniformity of results and permit the production of stereotype plates of uniform size, thereby avoiding the paper loss that is now incidental to the manufacture of newspapers because of the lack of uniformity in the size of the plates.

A further object is to provide a better quality of printing plates.

In practicing my invention I arrange the mats, face-to-face, in pairs, and stack these pairs with moistened pads between the backs of the mats. These pads preferably consist of heavy linen cloth which has been folded once to give two thicknesses. Prior to their Application filed August 9, 1928. Serial No. 384,780.

arrangement in the stack the pads are saturated with water and then run lightly through a wringer to insure uniform dampness. Each stack should comprise a suflicient number of pairs of pads to produce the plates of a complete edition of the newspaper or other matter to be printed and whenastack has'been formed a metal plate is placed on top of the rarest 0FFE if stack for the purpose of exerting sufficient pressure thereon to prevent any buckling of the mats and to keep the linen and mats in intimate contact. 7

The stack, with the metal plate thereon, is then placed in a closed chamber of sufficient size to permit air to freely circulate around all sides of the stack. This should preferably be arefrigeration chamber and any preferred method of refrigeration may be used. The temperature of the chamber is maintained above the freezing point until the mats are thoroughly and uniformly moistened and then the temperature is reduced to a point below freezing and the'inats are maintained at this temperature until they are to be used.

In orderto insure uniformity of moistening of the mats, before thetemperature of the chamber is reduced below the freezing point, a pan of water, or other means for supplying moisture to the chamber, may be employed to keep the atmosphere in a substantially saturated condition.

The stack of mats will be, under the procedure above set forth, moistened in a thoroughly uniform manner, throughout, by the fourthday after being put into the chamber and then the temperature should be reduced below the freezing point so as to freeze the mats to thereby retain their moisture content, without change, until the mats are to be used. On account of the frozen condition of the mats, when they are removed from the refrigerating chamber, there is less tendency for evaporation of the surface moisture while they are being handled and used in the matrix-rolling machine and the freezing of the mats seem to improve their conditlon and also the quality of the plates that are made therefrom.

Having thus described my invention what I claim is:

2 i V V 1,756,564

1. The hereindescribed method of preparing mats for use in making rinting plates,

i which consists in stacking a p urality of pairs of mats with the mats of each pair face-toface, and with moisture-containing pads between the respective pairs and then maintaining the stack in a substantially saturated atmos here in a closed chamber at a temperature a ove freezing for a sufficient time'to permit the matsto become thoroughly and' uniformly moistened throughout, and then freezing the mats. V

2. The hereindesc'ribe'cl method of preparing mats for use in making printing plates, which consists in stacking a plurality of pairs of mats with the mats of each pair face-toface, and withmoisture-containing pads between the respective pairs, subjecting the stack to a sufficient pressure to insure uniform contact between the mats and pads and to prevent the pads from buckling, then maintaining the stack in a substantially saturated atmosphere in a closed chamber above freezingtemperature for a sufiicient time to enable the mats to become uniformly moistened throughout, and then freezing the mats.

In' testimony whereof, I hereunto afiiX my signature. v

' EARLE MARTIN. 

